Generally, power cables such as a submarine cable and an underground cable include a watertight layer which suppresses permeation of moisture from the outside.
FIG. 1 schematically illustrates a structure of a cross section of the power cable disclosed in U.S. Pat. No. 4,472,597. As illustrated in FIG. 1, the power cable according to the related art may have a structure in which a conductor 1, an inner semiconducting layer 2, an insulating layer 3, an outer semiconducting layer 4, a metal shield layer 5, a conductive tape layer 8, a watertight layer 7, and an external jacket 6 are sequentially formed.
Here, when an aluminum laminated tape in which both sides of aluminum foil are coated with polyethylene is used as the watertight layer 7, the aluminum foil is likely to corrode and may be thus damaged by moisture penetrating the external jacket 6, thereby reducing the lifespan of the power cable.
FIG. 2 schematically illustrates a structure of a cross section of the power cable disclosed in U.S. Pat. No. 4,501,928. As illustrated in FIG. 2, the power cable according to the related art may have a structure in which a conductor 1′, an inner semiconducting layer 2′, an insulating layer 3′, an outer semiconducting layer 4′, a metal shield layer 5′, a semiconducting tape 6′, a watertight layer 7′, and an external jacket 8′ are sequentially formed.
Here, when a lead laminated tape in which both sides of lead foil are coated with polyethylene, polyvinyl chloride, or the like is used as the watertight layer 7′, the lead foil is heavy in weight and may thus prevent the manufacture of a lightweight power cable.
The watertight layers 7 and 7′ applied to the power cables according to the related art do not have adhesion strength enough to be adhered to the external jackets 6 and 8′ and may be thus separated from the external jackets 6 and 8′ due to an externally physical impact or a temperature change.
Accordingly, there is an urgent need for a power cable which is, when compared to existing power cables, lightweight, and includes a watertight layer which improves a corrosion resistance and is effectively suppressed from being peeled since the interlayer adhesiveness thereof is maintained regardless of an externally physical impact and a temperature change.